Fig. 7.
Catalase directly releases H2S from 1 mM DTT and this is inhibited by 1 mM carbon monoxide (CO). (A) Representative amperometric traces of H2S release from DTT alone (0) or when 1 mM DTT was added 10 min after 10 μM H2S was metabolized by 10, 20 or 50 μM catalase. Numbers in bold/italic indicate catalase concentration after H2S addition; plain numbers are from same curve as above showing H2S generated 10 min after DTT addition in same experiment. (B) Effect of catalase concentration on H2S release from 1 mM DTT without prior addition of H2S. All values are significantly (p<0.001) different from each other (mean +SE, n =3 replicates). (C) H2S released from 50 μM catalase metabolism of 1 mM DTT remains relatively constant for nearly 90 min. (D) Amperometric traces of H2S released from 50 μM catalase metabolism of 100 μM DTT in normoxia and hypoxia. In normoxia, H2S concentration increases then there is a relatively abrupt decrease in concentration. In hypoxia H2S concentration continues to increase until it is twice that in normoxia and it does not abruptly decrease. (E) H2S released from 50 μM catalase metabolism of 50 and 100 μM DTT in normoxia and hypoxia and duration of H2S response which is shorter in normoxia (mean +SE, n =3 replicates; all hypoxia are significantly (p<0.001) different from respective normoxia and all 50 μM DTT are significantly (p<0.001)different from 100 μM DTT). (F) Production of H2S from 100 μM DTT by 50 μM catalase in hypoxia (N2) and in hypoxia with 1 mM carbon monoxide (CO). Left, typical amperometric traces; right, average H2S production (mean +SE, n=3; *p=0.006).